Applicant claims priority under 35 U.S.C. xc2xa7119 of German Application No. 199 26 568.2 filed Jun. 11, 1999. Applicant also claims priority under 35 U.S.C. xc2xa7120 of PCT/DE00/01169 filed Apr. 14, 2000. The international application under PCT article 21(2) was not published in English.
The invention relates to a cooled piston for internal combustion engines with the features specified in the introductory part of claim 1.
Such pistons are known from DD 252 638 A1 and DE 41 34 530 A1, in connection with which the part of the wall serving for covering the downwardly open, ring-shaped cooling channel extending all around is realized in the form of an open sheet metal ring. Making use of its elastic deformation according to the Seeger ring principle, i.e. with initial tension in the radial direction, said ring is inserted in a groove extending on the inner circumference of the piston ring zone or outer circumference of the wall of the combustion chamber.
A piston crown part is known DE 42 08 037 C2 in connection with which the downwardly open cooling channel is covered by a fixed, tensioned cup spring. Said spring is divided in at least two parts and radially rests freely on the inside and outside against abutments on axially opposed sides.
A piston with a cooling channel in the crown of the piston is known from DE 39 91 677 T1, in connection with which provision is made for a baffle plate covering the lower open end of the cooling channel. The ends of said baffle plate are vertically bent off upwards in the zone of division in order to maintain a defined level of cooling oil in the cooling channel.
The drawback with the above embodiments is that the dwelling time of the cooling oil in the cooling channel has not been solved in a satisfactory manner to the desired extent.
Therefore, the invention is based on the problem of prolonging the dwelling time of the cooling oil in the cooling channel and to reinforce the Shaker effect of the cooling oil in order to achieve superior heat dissipation in the zones of the piston to be cooled.
Said problem is solved in connection with a piston of the type specified above by the features according to the characterizing part of claim 1.
Other useful variations according to the invention are contained in the dependent claims.